Extract silhouette spline from object(?)



I was wondering if anyone has stumbled across this situation and figured out an efficient solution or workaround.

I’ve been exploring various workflows to streamline the creation of parallel projected, technical drawings with their final destination inside Adobe Illustrator as vectors. Extracting internal lines from objects and exporting these into illustrator is fairly straightforward from an app like Rhino, using their “Make 2D” command.

The only part Rhino fails at is producing a clean, workable silhouette-outline to encompass the final illustration as a whole inside Adobe Illustrator.

The method that has been the most successful so far has been to import the geometry into C4D, and use Sketch & Toon’s ability to export sketch lines as illustrator files. The only problem is that this technique can take up to half an hour (on my computer) to generate an outline on a complex object, with all its internal lines culled. Long story short: This method works but takes a looong time to produce the outline.

Is there any alternative / faster method to produce a silhouette spline of a complex object inside C4D?

Possible methods:
(1) One idea is to take advantage of the (instantaneously) fast orange object outline that C4D generates on selected objects. Is that data in any way “extractable” as a basis for a spline?

(2) Because the camera angle is parallel, aligning an infinite light source to it, generates a very sharp shadow onto a surface behind the object - Is there a way to use that shadow to generate the desire silhouette spline?

If you have any ideas or creative solutions to this conundrum, I’d be very interested to hear them.

Cheers / Alex


Could it be an option to render it as an matte object (compositing tag) and create an outline from this in post?


For the first question :
Well, that outline is monocromatic, you could save a render from the Vieport Renderer and use a quick magic wand to mask it out in photoshop. I don’t know what vectorization process you could use for the rasterised outline. I use Corels vectorizer. You could reimport it in C4D’s vectorizer and export it in AI.


That’s not a bad idea. The only problem is that the client demands everything to be vector-based.
I suppose the result can be “image traced” inside of Illustrator but it would also require a very high-res render out of C4D to be accurate enough and would probably still require additional cleanup.

Thanks :slight_smile:


Export the shadow you created in the bottom image and then try the Vectorizer tool in the Splines menu on the imported bitmap to create splines. Render/Export the splines as needed.


There is the native vectorizer in C4D and the more advanced https://cinemaplugins.com/c4d-plugins/vectorizer-professional/

Render a high res alpha map and input it back maybe?


Wow, that’s a great plugin.
Maybe I can feed what the camera is seeing and pipe that into the plugin via the Camera Shader.

Thanks! / Alex